1. Field of the Invention
The present invention relates to a thin film transistor array substrate and a method of manufacturing the same, and more particularly relates to a thin film transistor array substrate that improves electrical characteristics of an oxide semiconductor layer and a method of manufacturing the same.
2. Description of the Related Art
A liquid crystal display device, one of the most widely used types of flat panel displays in recent years, typically includes two substrates with electrodes, and a liquid crystal layer between the substrates. The substrates adjust the amount of light passing through the liquid crystal layer by re-arranging liquid crystal molecules in the liquid crystal layer using a voltage applied to the electrodes.
In many contemporary liquid crystal display devices, an electric field generating electrode is provided to first and second substrates, respectively. In this configuration, a plurality of pixel electrodes are arranged in a matrix form on the first substrate (i.e., a thin film transistor array substrate), and one common electrode covers the entire surface of the second substrate.
In this liquid crystal display device, images are displayed by applying an individual voltage to each pixel electrode. To accomplish this, a thin film transistor, a three-terminal element switching the voltages that are applied to the pixel electrodes, is connected with the pixel electrodes. Also connected to the pixel electrodes are a plurality of wires including gate lines that transmit signals for controlling the thin film transistor, and data lines that transmit voltages for the pixel electrodes. These devices are all formed on the substrate.
This switching element can be divided into an amorphous silicon thin film transistor and a polycrystalline silicon thin film transistor, depending on the materials that form the channel region. As for the amorphous silicon thin film transistor, the mobility of charge is low at about 0.5 cm2/Vs, but it can achieve uniform electrical characteristics for wide display devices. Further, as for the polycrystalline silicon thin film transistor, the mobility of charge is high at about a few hundred cm2/Vs, but it is difficult to achieve uniform electrical characteristics for wide display devices.